Recent advances have been made to allow direct streaming of video and audio directly from one wireless communication enabled device to another. One such system is known as “Miracast.” Miracast is a trademark for a wireless (e.g. IEEE 802.11 family of wireless protocols or “Wi-Fi”) display protocol promulgated by the Wi-Fi Alliance. As used herein, the term Miracast refers to the current form of the Wi-Fi Alliance's display sharing protocol, also known as Wi-Fi Display (WFD). The Miracast specification is designed for streaming any type of video bitstream from a source device to a sink device. As one example, a source may be a smart phone, and a sink may be a television set. Although in typical IEEE 802.11 wireless networks, client devices communicate through an access point (AP) device, protocols exist (such as Wi-Fi Direct) that support direct device communications. The Miracast system uses such protocols for sending display data from one device to another, such as from a smart phone to a television or computer, or vice-versa. The Miracast system involves sharing the contents of a frame buffer and speaker audio of the source device to a remote display/speaker device (sink) over a Wi-Fi connection.
The Miracast protocol involves the source capturing the RGB data from the frame buffer and any PCM (Pulse Coded Modulation) audio data from the audio subsystem. The content of the frame buffer may be derived from application programs or a media player running on the source. The source then compresses the video and audio content, and transmits the data to the sink device. On receiving the bitstream, the sink decodes and renders it on its local display and speakers.
When a user plays an audio/video clip locally on a Miracast capable source device, the bitstream is decoded and rendered locally on the source display and then the audio/video content is captured, re-encoded and streamed to a Miracast capable sink device at the same time. The sink device then decodes and renders the same content on its display and speakers. Such operation is often called the “mirroring” mode.